1. Field of the Invention
The present invention relates to an agricultural machine comprising:                a central frame designed to be connected to a tractor so as to be towed by the latter, and provided with wheels in contact with the ground,        two work devices, each connected to the central frame by a first articulation and being able to be displaced between a transport position, in which each work device extends in a plane substantially parallel to the direction of advance of the machine, and a work position in which each work device extends in a plane substantially perpendicular to the direction of advance of the machine.        
2. Description of the Related Art
An agricultural machine of the drawn mower type, including a towable frame on which two mowing devices are articulated, is known from the document EP 1 616 474 A1. The frame is designed to be connected to a tractor so as to be towed by the latter, and is provided with wheels resting on the ground. The mowing devices are mounted on an articulation respectively on each respective side of the chassis so as to rock in a horizontal plane extending laterally between a work position and a transport position.
To this end, each of the mowing devices includes a support framework and a support arm, the support framework being connected to the support arm by an articulation having an axis substantially parallel to the direction of advance of the machine when the mowing device is unfolded in the work position. The support arm is connected to the frame by an articulation device including on one hand an articulation, the axis of which is substantially parallel to the direction of advance of the machine when the mowing device is unfolded in the work position, on another hand an articulation, the axis of which is substantially vertical, the articulations of the articulation device being situated close to one another. The articulation device is positioned on the front end of the frame.
In order to be moved from the work position to the transport position, each of the mowing devices in the work position is firstly raised vertically by means of the support arm, then each of the mowing devices is displaced towards the rear in a horizontal plane by means of the articulation having a substantially vertical axis situated on the front end of the frame, before being lowered to come to rest on an abutment element.
The mower described above presents a certain number of drawbacks.
Firstly, the width of the machine, when the mowing devices are folded in the transport position, remains relatively large. In fact, when each of the mowing devices is in the work position, it presents itself in a lateral view of the machine as a substantially parallelepipedic assembly, the horizontal dimension of which is greater than the vertical dimension. When each of the mowing devices is in the transport position, the total width of the machine is at least equal to the sum of the horizontal dimensions and therefore proves to be large.
Secondly, by defining the mowing width of a mowing device in the work position as being the dimension of the mowed part measured following a direction perpendicular to the direction of advance of the machine, the fact of increasing the mowing width by a certain amount results in an increase of an amount substantially equal to the total length of the machine when the mowing device is in the transport position. This increase comes to hinder the handling of the machine.
Thirdly, the equilibrium of the machine during work requires that in this position, the wheels resting on the ground are positioned behind the work devices, which determines at a relatively high value the wheelbase defined by the distance between the rotation axis of the wheels resting on the ground and the rotation axis of the rear wheels of the tractor. Now, as the frame has a fixed geometry, this wheelbase is constant whatever the position of the machine. Thus, in transport position, the relatively large wheelbase comes to hinder the handling of the machine when cornering.
Fourthly, the work devices, in the transport position, extend at a certain distance above a horizontal plane situated above the wheels resting on the ground, which raises the centre of gravity of the machine and therefore increases its instability during transport.